Telephony.



G. G. CUMMINGS.

TELEPHONY. APPLICATION FILED JULY 20, 1908 Patented Junezz, 1909 Ill? county of Cook and State of GEORGE G. CUMMINGS, OF WESTERN SPRINGS, ILLINOIS.

TELEPHONY.

Specification of Letters Patent. Application filed July 20, 1908.

Patented June 22, 1909.. serialize. 444,356.

To all whom it may concern:

citizen of Canada,.and subject of King Edward VII, residing at Western S rings, in the l llinois, have invented a certain new and useful Improvement in Telephony, of which the following is a full, clear, concise, and exact .description, reference being had to the accom anying drawings, forming a part of this specification. My invention relates to telephony, certain features thereof being applied to a telephone system including a telephone line, a transmitting station at which voice currents are impressed upon the line, a lurality of receiving stations having telep 10116 receivers included in conductors in bridge of the telephone line, and which conductors ofler differng degrees of effective resistance to the voice currents impressed thereupon by the transmittmg station, each bridge conductor that is nearer the transmitting statlon havlng more eiiective resistance than each more distant bridge conductor.

Other features of my invention are prefer- .ably applied to the teleIphone system generally outlined, though do not wish to be limited to the precise application of these latter features of my invention.

My invention will be well understood by reference to the accompanying drawing, in which Figure 1 shows one embodiment thereof, and Fig. 2 another embodiment thereof.

The telephone system to which I have adapted my invention includes a metallic circuit a which is shown as connecting a telephone station 1 (which, for example, may be a train despatchers office) with four or other number of telephone stations, 2, 3, 4 and 5. Each telephone station includes a bridge conductor 6 uniting the metallic sides of the telephone line a (though it is to be understood that I do not limit my invention to metallic telephone circuits), within which bridge conductor there is included at each station a telephone switch-hook c, a receiver (3, the secondaryf of an induction coil and a condenser g. Each bridge conductor 7) at the stations 2-, 3, 4 and 5 also includes a re tardation coil 0 that serves to determine the effective resistance offered to the talking current impressed upon said bridge conductor at the line. The primary of the induction coil at each telephone station is shown included in a local circuit with a transmitter h and a battery i. The retardation coils c at the different line stations are provided with adjustable cores, whereby the inductanceafiorded by said coils a may be adjusted, the adjustment of the coils 0 being such that the effective resistance of the bridge conductor at station 2 is. caused to be greater by the retardation coil 0 than the efiective resistance of the bridge conductors b at the other! train line stations that are more remote from the despatchers oflice 1 the effective resistance of the bridge conductor 6 at train line station 3 is made less than the effective resistance of the bridge conductor at the bridge conductors at the different train line stations, the effectiveness. of the voice cu;r-

rents received at each of such stations may be made approximately equal. This. is. due to the fact that the impedance or effective resistance of the different bridges is tapered in value from the despatc-hers end of the line to the other end thereof. F or example, it is possible with this arrangement to so adjust the effective resistance of the conductor 1) at station 2, that it is equal to the effective resistance of the corresponding conductor of the station at the other endot the line plus the line resistance.

In accordance with one feature of my in-. vention, there is provided at each stat on a shunt conductor 7c, which includes a retarda tion coil Z of low ohmic resistance. The cone ductor 7c and the local circuit for the trans mitter it includes. each a pair of contacts 012, and n, respectively, the contacts of each of the sets m and n being normally in separated relation. The contacts of both sets are sf multaneously engaged upon the operation of a key 0, the operation oi? which key is to occur'when the receiver d of the associate station isremoved from,- its switch-hook o and when the party at suchstation. s; to talk. When the party at. such station-is to listen, the button 0 is released. 'Ifi'the, train despatcher or other party is talking at the station 1, the receiver thereat is shunted by resistance is established about the telephone receiver at. By this feature of my invention I can enabled to eliminate a large portion of the eifectlve resistanceto the outgoing voice I currents that are nnpressed upon the second ary f as a consequence of the operation of the transmitter IL. The conductor 7r atIeach of the stations 2, 3, 4 and 5 not only establishes a shunt about the telephone receiver d at each of said stations when said conductor-7c closed at m at each station, but said conductor k at each station is also so connected as to shunt the retardation coil 0 thereat as 2 well. By shunting the receiver (1 and retardation coil 0 when talking, the effective resistance ofieredto theflow ofimpressed voice currents from the. secondary f to the line is not only reduced, but side tones at the receivers 11 are eliminated, which is also the case with the receiver at station 1 when the shunt conductor 7c thereat is closed at m. It is to be understood that the key 0 ate station is operated only when voice currents are to-be im ressed upon the line at such station vand t at such key 0 is to be released when voice currents are to be received at such station, the strength of the batteries i incidentally being saved .by opening the transmitter circuits during the time the receivers have the shunts removed therefrom. -The retardation coil Z included in each shuntconductor is has an adjustable core to vary the effect of the shunt upon the circuit including the receiver. The 1purpose of this adjustab eimpedance whic -is normally low in value, is to permit voice'currents to pass through the receiver, provided the despatcher desires to interrupt the person 5 talkin at any one of the stations. It being desira le to have this impedance low so as not to dissociate outgoing voice currents from the stations, it is'found preferable to make it adjustable so thatthe break in feature; described above may be obtained.-

In practice, it is found only necessary that the person talking should receive enough current to know that the despatcher is on the I line, in which event the'party talking releases the. key 0 and releases the full talking current fi'om the line-.- The effective resistance ofiered b" the smallretard'ation coil-Z 'ateach' train e station that is nearer the II 5 densers 2 being substituted for the retard'aductance path of comparatively low effective tion coil 0 the capacity of, these condensers increasingwith the distance of the train line stations from the 'despatchers ofiice. In other respects the system shown in Fig. 2 is similar to the system shown in Fig. 1.

In the descrlption of the operation thus far given, station 1 has been considered as. the sending or transmitting station, for by the features of the system so far described the voice currents emanating from such sending or transmitting station were divided eripally among the other listening stations,

w ich thus became receiving stations.

In considering another feature of my invention, now to be described, each ofthe 8O outer or line stations 2, 3, 4 and 5 may be takenas a sending-or transmitting station. and station No. 1 as a central or receiving station, it being an object of my present in- I vention to cause the tele hone receiver at such receiving station to e operated with the same degree of efiectiveness by all of the "remaining, or transmitting, stations, so that conversation maybe transmitted from the distant stations to the receiving station with the same effectivenessas from the nearer stations. In accomplishin the present object of my invention,the vdltages of the batteries i at the diiferent outlying or transmitting stations are adjusted with regard to the resistances intervenin between the receiving station and the ot er stations uponthe line, the voltage of each battery i'that is nearer the receiving station being less than the voltage of each more distantbattery i. Byway of example, let it be assumed that the resistance of each side of the metallic circuit a between stations 1 and 2 istwenty-five ohms, the resistance of each side .of the me-' I tallic circuit a, between stations 1 and 3 is one hundred fifty ohms, the resistance of each side of the metallic circuit a between stations 1 and 4 is two hundred seventy-five ohms, the resistance of each side of the metallic circuit a between stations 1 and 5 is five hun dred twenty-five ohms; in such case the'voltages of the batteries at stations l-to 5, inclusive, may be ten volts for station 1-, six, volts for station 2, nine volts for station 3, twelve volts for station 4,, and sixteen volts for station 5. The ap aratus that may well be employed at eacho the stations may be a #233 or #229 Western -Electric Company transmitter, a #13 Western Electric induction coil, and a #128 Western'Electric 'Comany'receiver, which are standard devices to he found upon the market. The condensers g that are desirably included in the bridge conductors b may be two microfarad condensers the retardation coilsc may be of two hun- 12 5. I

dred ohms resistance each,'and the retarda tion coils 1 may be of "one ohm resistance each- By having the batteries iat the different transmittin stations of properly dif-' ferentvoltages, t e inequality oi the re- 130 sistances between the transmitting stations phone line, a transmitting station at which and the receiving station ma 7 be compensated for, whereby the telephone receiver at at the receiving station 1 is operated with the same degree of effectiveness by voice currents of similar value generated at the transmitting stations irrespective of the distances of such stations from the receiving station, for the wattage or energy traversing the receiver d at the receiving station 1 is the same with'respect to the currents flowing from the transmitting stations under the conditions named.

, My invention may be adapted to any tele-' phone line having a receiving station and a plurality of transmitting statlons Within reasonable distance of the receiving station, the voltages of the batteries at the transmitting stations being suitably proportioned with respect to the resistances intervening between saidtransmitting stations and the receivlng station, so that thewattage of the current traversing the telephone receiver at the receiving station wil be the same as a consequence of the generation of voice currents of similar value at the transmitting stations.

It will be seen that I have provided a telephone system-including a telephone line, a telephone station thereon, a plurality of other telephone stations thereon, and means for equalizing the voice currents or wattage received at one station as a result of equivalent transmitter operations at other stations.

YVhil'e I have herein shown and particularly described preferred embodiments of my invention and the adaptation thereof to train line circuits, I do not wish to be limited thereto, as changes may readily be made without de arting from the spirit of the invention.

aving thus described my invention, I claim as new and desire to secure by Letters Patent the following 1. A telephone system including a telephone line, a transmitting station at which Voice currents are impressed upon the line, a plurality of telephone stations having telephone receivers included in conductors in ridge of the telephone line, and which conductors oiier difi'ering degrees of effective resistance to the voice currents impressed thereupon by the transmitting station, each bridge conductor that is nearer the transmitting station having more effective resistance than eachmore distant bridge conductor, transmitters also at the latter stations, circuits for the transmitters, induction coils having primaries in the transmitter circuits and secondaries in the bridge conduc tors containing the receivers, shunts about the effective resistance in said bridge conductors for conveying outgoing voice currents impressed upon the secondaries, and switching devices for opening and closing said shunts and the associate transmitter circuits.

2. A telephone system including a televoice currents are impressed upon the line, a plurality of telephone stations having telephone receivers included in conductors in bridge of the telephone line, and which conductors oll'er dillering degrees of impedance to the voice currents impressed thereupon by the transmitting station, each bridge conductor that is nearer the transmitting station having more impedance than each more distant bridge conductor, transmitters also at the latter stations, circuits for the transmitters, induction coils having primaries in the transmitter circuits and secondaries in the bridge conductors containing the receivers, shunts about impedance in said bridge conductors for conveying outgoing voice currents impressed upon the secondaries, and switching devices for opening and closing said shunts and the associate transmitter circuits.

3. In a telephone system, the combination with a telephone receiver, of a telephone transmitter, circuits for said receiver and transmitter, an induction coil whose primary is in the transmitter circuit and whose secondary 1s in the receiver circuit and in the path of outgoing voice-currents occasioned by operation of the transmitter, a shunt at a transmitting station about effective resistance in cluded in the circuit of said secondary .t'o'r conveying outgoing voice currents impressed upon the secondary, and switching mechanism controlling the continuity of said shunt and the transmitter circuit.

4. In a telephone system, the combination with a telephone receiver, of a telephone transmitter, circuits for said receiver and transmitter, an induct-ion coil whose primary is in the transmitter circuit and Whose secondary is in the receiver circuit, a shunt at a transmitting station about the receiver for conveying outgoing voice currents impressed upon the secondary, and switching mechanism controlling the continuity of said shunt and the transmitter circuit.

5. A telephone system including a telephoneline, a transmitting station at which Voice currents are impressed upon the line a plurality of telephone stations having telephone receivers included in conductors in ridge of the telephone line, and which conductors ofie'r differing degrees of effective resistance" to the voice currentsimpressed thereupon by the transmitting station, each bridge conductor that is nearer-the transmitting station having more eitective resistance than each more distant bridge conductor, transmitters also at-the latter stations, circuits for the transmitters, induction coils having primaries in the transmitter circuits and secondaries in the bridge conductors containing the receivers, and means for reducing effective resistance of said bridge conductors.

6. A telephone system including a telephone line, a transmitting station at which voice currents are impressed upon the line, a

ductors offer difiering degrees of impedance to plurality of telephone stations having telethe voice currents impressed thereuponbythe hone receiver's included in conductors in bridge of the telephone line, and which conductors offer differing degrees-of impedance to the voice currents lmpressed thereupon by the transmittingstation, each bridge conductor that is nearer the transmitting station I having more impedance than'each more distant bridge conductor, transmitters also at the latter stations, circuits for the transmitters, induction coils havlng primaries in the transmitter 0110111128 and secondaries 1n .the

bridge conductors containing thereceivers,

and means for reducing impedance of said bridge conductors. v 7'. In a tele hone system, the. combination with a telep one receiver, of altelephone transmitter, circuits for said receiver and transmitter, an induction coil whose primary is .in the transmitter circuit' and whose secondary is in the receiver circuit, and means at the telephone station where the above apparatus islocated for reducing effective resistance in thep'ath of voice currents impressed upon the secondary.

8. In atele hone system, thecoinbination with a telep one receiver, of a telephone associate transmitter clrcuits. 6O

transmitter, circuits for said receiver and transmitter, an induction coil whose primary is in the transmitter circuit and whose sec-r.

ondary is the receiver circuit and in the path of' outgoing voice-currents occasioned. y operation of the transmitter, and means for excluding the receiver from'thendirect path ofvoice currents impressed uponthe secondary. i r

9.. A telephone system including a telephone line, a transmitting station at which voice currents are impressed upon, the line, a plurality of telephone; stations having, telehone receivers =1ncluded in icondu'ctors in 7 ridge of the telephone line, and which con ondary is inthe receiver circuit andin the 'ath of outgoin voice-currents occasioned ductors offer differing degreesof'eifective re- 4 sistance to the voice currents impressed cuits for the transmitters, induction coils halving primaries in the transmitter circuits and secondaries in the bridge conductorscontaining the receivers, shunts about effective resistance in said bridge conductors for con 'veying outgoing voice currents impressed upon the secondaries,.and switching devices for opening and closing said shunts and the -'10. A telephone system including a telephone line, a transmitting station at which voice currents are impressed upon thelineg a plurality of telephone stations having telehone. receivers lncluded in conductors in ridge of the telephone 1ine, and which contransmitting station, each bridge conductor that is nearer the transmitting station havingmore impedance than each more distant bridge conductor, transmitters also at the lat.- ter stations, circuits for the transmitters, induction coils having primaries in the transmitter circuits and secondaries inthebridge coilductors containing the receivers, shunts about impedance in said bridge conductors for con- Veying outgoing voice currents impressed upon the secondaries, and switching devices for opening and closing said shunts and the assoclate transmitter circuits.

11. In a telephone system, the combination with a telephonereceiver, of a telephone transmitter, circuits for said receiver andtransmitter, an induction coil whose primary is in the transmitter circuit and whose secondary is in the receiver circuit and in the path of outgoing voice-currents occasioned y operatlon of the transmitter, a shunt at a transmitting station *for. reducing eflective resistance in the path of voice currents impressed upon the secondary, and switching mechanism controlling the continuity of said v shunt 12. In a telephone system, the combina-.

tion with atelephonereceiver, of a telephone transmitter, circuits 'for said receiver and,

transmitter, an induction .coil Whose primary is in the transmitter, circuit and whose secondary is in the receiver circuit, a shunt at a transmitting station about the receiver for conveying outgoing voice currents impressed u'ponthe secondary, and switching mechan. ism controllingthe continuity of said shunt.-

13. In a telephone system, the combina I tion with a telephone receiver, of a telephone transmitter, circuits for said receiver and transmitter, an induction coil whose primary" is' in the transmitter circuit and, whose secy operation of t e transmitter, a'shunt 'at a transmitting station about impedance for a plurality of telephone stations having telephone receivers included in conductors in ridge of the telephone line, and which conductors offer differing degrees of effective re' sistance' to the voice currents impressed thereupon by the transmitting station, each bridge conductor, that is nearer the transmit ting station having more effective resistance than each more distant bridge conductor,

transmitters also; at the latter stations," jcircuits 'for the transmitters, induction-coilshaving primaries in the transmitter circuits and secondaries in the bridge conductors containing-the receivers, shunts about effective resistance in said bridge conductors for conveying outgoing voice currents impressed upon thesecondaries, and switching devices for opening and closing said 'shunts'and the associate transmitter circuits, said shunts containing difiering degrees of effective resistance, each shunt that is nearer the transmitter station havin'ginoreefiective resistance thaneach more-distant shunt.

15. A telephone system including a telephone line, a transmitting'station at which voice currentsare impressed-upon the line, a plurality of telephone stations having telephone "receivers included in conductors in ridge of the telephone'line, and which conductors offer differing degrees of impedance to the voice current impressed thereupon bv the transmitting station, each bridge coriductorthat is nearer the transmitting station 'having more impedance than each more-distant bridge conductor, transmitters also at the latter stations, circuits for the transmitters, induction coils having primaries in the transmitter circuits and secondaries in the bridge conductors containing the receivers,

shunts about impedance in said bridge conductors for conveying outgoing voice currents impressed upon the secondaries, and

switching devices 'for opening and closing said shunts and the associate transmitter circuits, said shunts containing differing degrees of impedance, each shunt that is nearer the transmitter station having more effective resistance than each more distant shunt.

16. A telephone system including a telephone line, a transmitting station at which voice currents are impressed upon the line, a plurality of telephone stations having telephone receivers included in conductors in ridge of the telephone line, and which conductors ofier differing degrees of effective resistance to the voice currents impressed thereupon by the transmitting station, each bridge conductor that is nearer the trans- .mitting station having moreeiiective resistance than each more distant bridge con-- ductor, transmitters also at the latter stations, circuits'for the transmitters, induction tion having more efiective rcsistancethan catch more distant shunt.

'17; In a telephone system including a'telephone line, a transmitting station at which voice currents are impressed upon the line, a plurality of telephone stations having telephone receivers included in conductors in ridge of the telephone line,-and which con. ductors oiier differing degrees of impedance coils having primaries in the transmitter cirto the'voice currents impressed thereupon by the transmitting station,reach bridge conductor that is nearer. the transmitting station having more impedance than each'more distant bridge conductor, transmitters also at the latter stations, circuits for the transmitters, induction coils having primaries in the trans'mittercircuits and secondaries in the bridge conductors containing the re- I ceivers, shunts containing difiering degrees of impedance, each shunt that is nearer the transmitter station having more etl'ective resistance'than each more distantshunt.

1'8. A telephone system including a telephone line, a telephone station thereon, a plurality of other telephone stat-ions thereon, means for equalizing the voice currents received at one station'as aresult of equivalent transmitter operations at other stations, bridge conductors at'each of thelatterstations containing telephone receivers and upon which outgoing voice currents at the latter stations are impressed, and means for reducing'eflective resistance of said bridge conductors when outgoing voice currents are impressed thereupon.

' 19. A telephone system including a telephone line, a telephone station thereon, a plurality of other'telephonc stations thereon, means for equalizing the wattage of voice 95 currents received at one station as a result of equivalent transmitter operations at the other stations, bridge conductors at each of the latter stations containing telephone re- 1 ceivers and upon which outgoing voice cur- 1 o rents at the latter stations are impressed, and means for reducing eil'ective resistance of said bridge conductors-when outgoing voice currents are impressed thereupon.

20. A telephone system including a tele- 105 phone line, a telephone station thereon, a plurality of other telephone stationsthereon, means at each of'thc latter stations for equalizing the voice currents received at the-first station as a result of equivalent transmitter 110 operations at other stations, bridge conductors at each of the latter stations containing telephone receivers and upon which outgoing voice currents at the latter stations are impressed, and means for reducing efl'ect- 115 ive resistance'ofsaid bridge conductors when outgoing voice currents are impressed there- 21. A telephone system including a telephone line, a telephone station thereon, a plurality of other telephone stations thereon, l means at each of the latter stations for equalizing the wattage of voice currents received at the first station as a'rcsult of equivalent i transmitter operationsat the other stations, bridge conductors at each of the latter stai tions containing telephone receivers and upon-which outgoing voice currents at the latter stations are impressed, and means for i reducing effective resistance of said bridge 1B0 conductors when outgoing voice currents are impressed thereupon.

22. A telephone system including a telephone line, a telephone station thereon, a plurality of other telephone stations at difi'ering distances from the former station, means for supplying the transmitter at each of the -latter stations with differing voltages of transmitter-current, the voltage at each of the latter stations that is nearer the first station being less than that at each of the latter stations more distant from the first station, bridge conductors ,at each of thelatt-er stations containing telephone receivers and upon which outgoing voice currents at the latter stations are impressed, and means for reducing effective resistance of said bridge conductorswhen outgoing voice currents are impressed'thereupon.

23. A telephone'system including a telehone line, a telephone station thereon, a, plurality of other telephone stations at differing distances from the former station, local transmitter circuitsat the latter stations, sources of current in said local circuits having differing voltages, the voltage'of the source of current at each of the latter sta-x tionsthat is nearer the first station being less than that at each of the latter stations more distant from the first station, bridge conductors at each of the latter stations containing telephone receivers and upon which outgoing voice currents at the latter stations are impressed, and means for reducing effective resistance of said bridge conductors when outgoing voice currents are impressed thereupon.

24. A telephone system including a telephone line, a telephone station thereon, a

plurality of other telephone stations thereon, means at each of the latter stations for equalizing the voice currents received at the first station as a result of equivalent transmitter operations at other stations, bridge conductors at each of the latter stations containing telephone receivers and upon which outgoing voice currents at the latter stations plurality of other telephone stations thereon,

means at each of the latter stations for equalizing the voice currents received-at the first station as a result of equivalent transmitter operations I at other stations,- bridge conductors at each of the latter stations cont-aining telephonereceivers and upon which outgoing voice currents at the latter stations are impressed, said bridge conductors 1ncluding differing degrees of impedance to the voice currents impressed thereupon by the.

first station, each bridge conductor that is nearer said first station having more imedance than each more distant bridge conductor, and means at the latter stations for excluding said impedance from said bridge conductors when outgoing voice currents are impressed upon said conductors. 26. A telephone system including a telephone line, a -telepho ne station thereon, a-

plurality of other telephone stations thereon, means at each of the latter stations for equalizing the voice currents received at the first I station as a result of equivalent transmitter operations at'other stations, bridge co'nduc tors at each of the latter stations containing telephone receivers and'upon which outgoing voice currents at the latter stations are impressed, said bridge conductors including diifering degrees of effective resistance to the voice currents impressed thereupon by the first station, each bridge conductorthat is nearer said first station having more effective resistance than each more distant bridge conductor, shunts about said 'efiective resistances, and switching mechanism for' controlling the continuity of said shunts.

27. A telephone system including a telephone line, a telephone station thereon, a plurality of other telephone stations thereon, means at each of the latter stations for equalizing the voice currents received at the first station as a result of equivalent transmitter operations at other stations, bridge conductors at each of the latter stations containing telephone receivers and upon which outgoing voice currents at the latter stations are impressed, said bridge conductors including differing degrees of impedance to the voice currents impressed thereupon by the first station, each bridge conductor that is nearer said first station having more impedance than each more distant bridge conductor,- shunts about said impedance, and switching mechanism for controlling the continuity of said shunts. i 4

28. A telephone system'including a telephone line, a telephone station thereon, a

plurality of other telephone stations thereon, means at each of the latter stations for equalizing the voice currents received at the first station as a result of equivalent transmitter operations'at other stations, bridge conductors at each of the latter stations containing telephone receivers and upon which outgoing voice currents at the latter stations are impressed, said bridge conductors; including difiering degrees of eflejct ive resistance to the voice currents impressed thereupon by the first station; each bridge conductor that is nearer said first station having more effective resistances than each more distant bridge conductor, shunts about said effective resistances, said shunts includ- I degrees I said shunts.

29. A; telephone system including a telephone line, a telephone station thereon, a plurality of other telephone stations thereon,

-means at each of the latter stations for equalizing the voice currents received at the first station as a result of. equivalent transmitter operations at other stations, bridge conductors at each of the latter stations containing telephone receivers and upon which outgoing voice currents at the latter stations are impressed, said bridge conductors including differing degrees of impedance to the voice currents impressed thereuponby the first station, each bridge conductor that is nearer said first station having more impedance than each more distant bridge conductor, shunts about said impedance, said shunts including differing degrees of impedance, each shunt that is nearer the said first station having more impedance than each more distant shunt, and switching mechanism for controlling the continuity of said shunts.

' phone line, a

30. A telephone system including a telephone line, a telephone station thereon, a plurality of other telephone stations thereon, means for supplying the transmitter at each of the latter stations with difiering voltages of transmitter current, the voltage at each of the latter stations that is nearer-the first station'being less than that at each of the latter stations more distant from the first station, bridge conductors at each of the latter stations containing telephone receivers and upon which outgoing voice currents at the latter stations are impressed, said bridge conductors including, difiering degrees of effective resistance to the voice currents impressed thereupon by the first station, each bridge conductor that is nearer said station having more effective resistance than each more distant bridge conductor, shunts about said effective resistance, and switching mechanism for controlling the continuity of said shun ts.

31 A telephone system includinga telemeans for supplying the transmitter at each of the latter -stations with differing voltages of transmitter current, the voltage at each of the latter stations that is nearer the first station being less than that at each of the latter stations more distant from the first station, bridge conductorsat each'of the telephone station thereon, a plurality of other telephone stations thereon,

latter stations containing telephone receivers and upon which outgoing voice cur.- rents at the latter stations are impressed, said bridge eonductors including differing of impedance to the voice currents impressed thereupon by the first station, each bridge conductor first station'having more impedance than each more'distant bridge conductor, shunts I about said impedance, and switching mechanism for controlling shunts. J

32. A telephone system including a telephoneline, a telephone station thereon, a plurality of other telephone stations thereon,

the continuity of said means for supplying the transmitter at each of the latter stations with difiering voltages of transmitter current, the voltage at each of the latter stations that is nearer the first station being less than that at each of the latter stations more distant from the first station, bridge eonductors'at each of the latter stations containing telephonereceivers and upon which outgoing voice currents atthe latter stations are impressed, said bridge conduetors including differing degrees of effective resistance to the 'voice currents im: pressed thereupon by the first station, each that is nearer said ridge conductor that is nearer said first station having more effective resistances than each more distant bridge conductor, shunts about said effective resistances, said shunts including differingde'grees of efiective resistance, each shunt that is nearer first station having more effective resistance than each more distant shunt, and switching mechanism for controlling the continuity of said shunts.

33. A telephone system including a telephone line, a telephone station thereon, a plurality of other telephone stations thereon, mcansfor supplying the transmitter at each of the latter stations with differing voltages of transmitter current, the voltage at each of the latter stations that is nearer the first station being less than that at each of the latter stations more distant from the first station, bridge conductors at each of the latter stae tions containing telephone receivers an upon which outgoing voice currents at the the said latter stations are impressed, saidbridge con- 34. A telephone system including a tele-' phone line, a telephone station thereon, a

lurality of other telephone stations there on, ocal transmitter circuits at the latter sta- I tions, sources of current in said local circuitsv having different voltages, the voltage of each source of current at each of the latter stations that is nearer the first station being less than that at each of. the latter stations more distant from the firststation', bridge conductors at each of the latter stations containing 10 telephone receivers'and upon which outgoing .voice currents at the latter stations are im pressed, said bridge conductors including differing degrees of effective resistance to the voice currents impressed thereupon- Tby the first station, each bridge conductor that is nearer said first station having more effective resistance/than each more distant bridge .con-

ductor, shunts about said effective resistances, and switching mechanism for control ling the continuity of said shunts.

" 35. A telephone system including a telephone line, a telephone station thereon, a lurality of other telephone station's thereon, ocal transmitter circuits at the latter stations, sources of current in said local circuits having difierent voltages, thevoltage of each source of current at each of the latter stations that is nearerthe first station being less than that at. each of the latter stations more. distant from'the first station, bridge-conductors at each of the latter -stations containing telephone receivers and upon which outgoing "voice'currents at the latter stations are impressed, said bridge conductors including differing degrees ofimpedance to" the voice currents impressed thereupon by the first station, each bridge conductor thatis nearer said first station;having more impedance than each moredistant bridge conductor,

40 shunts about said impedance, and switching mechanism for controlling the continuity of said shunts. i

.36. A telephonesystem including a telephone line, a telephone station thereon, a lurality of other telephone stations thereon,

I Focal transmitter circuits at the latter sta-' tions, sources of current in saidlocal circuitsv having different voltages, the voltage of each source of current at each of the latter stationsthat is nearer the first station being less than that at each of the latter stations more distant from the firststation, bridge co-nductors at each of the latter stations containing telephone receivers and uponwhich outgoing voice currents atthe latter stations are im- "pressed, said bridge conductors including differing degrees of effective resistance to the voice currents impressed thereupon by the 1 first station, each bridge conductor that is 6 .nearer'said first station having more effective resist? nces than each more distant bridge conducton'shunts about said effective resist ances, 'sa'id, shunts including differing 'degrees of effective resistance, 'each shunt that is-nearerthe said first station having more effective resistance than each more distant shunt, and switching mechanism for controlling the continuity of said shunts 37. A telephone system including a telephone line, a telephone station thereon, a plurality ofother telephone stations thereon,

localtransmitter circuits at the latter sta tions, sources of current in said local circuits having different voltages, the voltage of each source of current'at each of the latter stations that is nearer the first station being less than that ateach'of the latter stations more distant from'the first station, bridge conductors at each of the latter stations containing tele phone receivers and upon ..Which outgoing voice currents at the latter stations are 1mpressed, said bridge conductors including.

differing degrees of impedance to the'voicecurrents impresse thereupon by' the .firs't station, each bridge conductor that is nearer. said first station having morelmpedance than each more distant bridge conductor,

shunts about said'impedance, said shunts in- I eluding differing degrees of impedance, each shunt that is nearer the said first station having'more impedance than each more distant shunt, and switchlng mechanism for controlling the continuity of said shunts.

38. A telephone system including a telephone line, a telephone station thereon, a

plurality of other telephone stations thereon,

local transmitter circuits at the latter stations, sources of current in said local circuits having different voltages, the voltage ofeach source of current at each of the latter stations that is-nearer the first station'being. less than that at each of the'latter stations more dis tant from the first station, bridge conductors at each of the latter stations containing tele phone receivers and upon which outgoing voice currents at the latter stations are impressed, said bridge conductors including difiering degrees of effective resistance tothe voice currents impressed thereupon by the first station, each bridge conductor that is nearer said first station having more effective resistance than each more distant bridge con- 'ductor, shunts about said effective re's1sttaining telephone receivers and upon-which outgoing voice currents at the latter stations are impressed, said bridge conductors including differing degrees of impedance to the voice currents impressed thereupon by the first station, each bridge conductor that is nearer said first station having more impedance than-each more distant bridge conductor,

phone line, a telephone station thereon, a

pluralityof other telephone stations thereon, local transmitter circuits at the latter stations, sources of current in said local circuits having dillerent voltages, the voltage of each source of current at each of the latter stations that is nearer thefirst station being less than that at each of the latter stations more distant from the first station, bridge conductors at each of the latter stations containing telephone receivers and upon which outgoing voice currents at the latter stations are impressed, said bridge conductors including ditfering'degrces of effective resistance to the voice currents im ressed thereupon by the first station, eac bridge conductor that is nearer said first station having more 'eiiective. resistances than each more distant bridge conductor, shunts about said effective resistances, said shunts including differing degrees of effective resistance, each shunt that is nearer the said first station having more effective resistance than each more distant shunt, and switching mechanism controlling the continuity of said transmitter circuits and said shunts.

41. A telephone system including a telephone line, a telephone station thereon, a plurality of other telephone stations thereon,

local transmitter circuits at the latter stations, sources of current in said local circuits having different voltages, the voltage of each source of current at each of the latter stations that is nearer the first station being less than that at each-of the latter stations more distant from the firststation, bridge conductors at each of the latter stations containing telephone receivers and upon which outgoing voice currents at the latter stations are impressed, said bridge conductors including diflering degrees of impedance to the voice currents impressed thereupon by the first station, each bridge conductor that is nearer said first station having more iiu-- pedance than each moredi'stant bridge cone.

ductor, shunts about said impedance, said shunts including differing degrees of iinpe-- dance, each shunt that is nearer the said first station having more impedance than each more distant shunt, and switching mechanism for controlling the continuity of said transmittercircuits and said shunts.

In witness whereof, I hereunto subscribe my name this 18th day of July A. D., 190S.

GEORGE O, CUMMINGS.

Witnesses:

L. G. STROH, G. L. CRoeo. 

